You can still follow Bill Ackman's trades. Here are his biggest investments right now.Bill Ackman is one of the best-known billionaire investors in the world. Despite his star power, he failed to launch a publicly traded investment fund last month, as demand fell short of expectations.Ackman planned to launch a closed-end fund called Pershing Square USA, which would have put him in charge of investing billions of investors' dollars. While he originally planned to raise $25 billion for the fund, he significa ...